/*
 * Copyright 2018 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrMtlUniformHandler_DEFINED
#define GrMtlUniformHandler_DEFINED

#include "include/private/base/SkTArray.h"
#include "src/base/SkTBlockList.h"
#include "src/gpu/ganesh/GrShaderVar.h"
#include "src/gpu/ganesh/glsl/GrGLSLUniformHandler.h"

#include <vector>

// TODO: this class is basically copy and pasted from GrVkUniformHandler so that we can have
// some shaders working. The SkSL Metal code generator was written to work with GLSL generated for
// the Ganesh Vulkan backend, so it should all work. There might be better ways to do things in
// Metal and/or some Vulkan GLSLisms left in.
class GrMtlUniformHandler : public GrGLSLUniformHandler {
public:
    static const int kUniformsPerBlock = 8;

    enum {
        kUniformBinding = 0,
        kLastUniformBinding = kUniformBinding,
    };
    static constexpr int kUniformBindingCount = kLastUniformBinding + 1;

    // fUBOffset is only valid if the SkSLType of the fVariable is not a sampler
    struct MtlUniformInfo : public UniformInfo {
        uint32_t fUBOffset;
    };
    typedef SkTBlockList<MtlUniformInfo> UniformInfoArray;

    const GrShaderVar &getUniformVariable(UniformHandle u) const override
    {
        return fUniforms.item(u.toIndex()).fVariable;
    }

    const char *getUniformCStr(UniformHandle u) const override
    {
        return this->getUniformVariable(u).c_str();
    }

    int numUniforms() const override
    {
        return fUniforms.count();
    }

    UniformInfo &uniform(int idx) override
    {
        return fUniforms.item(idx);
    }
    const UniformInfo &uniform(int idx) const override
    {
        return fUniforms.item(idx);
    }

private:
    explicit GrMtlUniformHandler(GrGLSLProgramBuilder *program)
        : INHERITED(program),
          fUniforms(kUniformsPerBlock),
          fSamplers(kUniformsPerBlock),
          fCurrentUBOOffset(0),
          fCurrentUBOMaxAlignment(0x0)
    {}

    UniformHandle internalAddUniformArray(const GrProcessor *owner, uint32_t visibility, SkSLType type,
        const char *name, bool mangleName, int arrayCount, const char **outName) override;

    SamplerHandle addSampler(const GrBackendFormat &, GrSamplerState, const skgpu::Swizzle &, const char *name,
        const GrShaderCaps *) override;

    int numSamplers() const
    {
        return fSamplers.count();
    }
    const char *samplerVariable(SamplerHandle handle) const override
    {
        return fSamplers.item(handle.toIndex()).fVariable.c_str();
    }
    skgpu::Swizzle samplerSwizzle(SamplerHandle handle) const override
    {
        return fSamplerSwizzles[handle.toIndex()];
    }
    uint32_t samplerVisibility(SamplerHandle handle) const
    {
        return fSamplers.item(handle.toIndex()).fVisibility;
    }

    void appendUniformDecls(GrShaderFlags, SkString *) const override;

    const UniformInfo &getUniformInfo(UniformHandle u) const
    {
        return fUniforms.item(u.toIndex());
    }

    UniformInfoArray fUniforms;
    UniformInfoArray fSamplers;
    skia_private::TArray<skgpu::Swizzle> fSamplerSwizzles;

    uint32_t fCurrentUBOOffset;
    uint32_t fCurrentUBOMaxAlignment;

    friend class GrMtlPipelineStateBuilder;

    using INHERITED = GrGLSLUniformHandler;
};

#endif
